The field of the invention pertains to closures for bottles, jars and other containers and, in particular, to caps for containers wherein a full or partial vacuum is to be maintained in the container until the cap is removed to obtain the contents. The field, however, is not limited to vacuum packaging but also includes containers wherein a partial vacuum can be maintained although the contents are not initially packed under partial vacuum conditions and carbonated beverages wherein the contents are packed under pressure.
Freshness and tamper monitoring of the contents of an unopened container continues to be of utmost importance in the packaging industry whether for food and consumer items or items related to health care. Means commonly used to indicate that the vacuum within a sealed container has not been lost or the contents have not spoiled include a cover with a depressed button area. With the loss of vacuum or the generation of gasses by noxious bacteria the depressed area will extend outwardly giving an obvious indication of possible danger.
With other containers such as cans, the lack of an audible inrush of air when the can is initially opened or the outward ejection of contents from the can when the can is initially opened indicate a failure of the sealing of the packaging or the generation of gasses by noxious bacteria.
Closures for containers, especially small closures such as bottle caps, do not readily indicate the failure of the seal despite the variety of means externally applied, such as shrink fit plastic wrappers to assure that the caps have not been removed. With the advent of plastic bottles, jars and other plastic packaging, one no longer can readily assure that freshness has been retained and that tampering has not occurred. Plastic bottles and jars permit tampering to be easily accomplished by means of a hypodermic needle or a razor slit along the mold parting line across the bottom of the bottle or jar.
With a view toward providing a cap or closure that more readily and obviously indicates a failure of the sealing of the container and a loss of freshness or possible tampering, the applicant has invented the closures disclosed below.